Cats with murmers - when to investigate?

Re: Cats with murmers - when to investigate?

mariette asselbergs — Sun, 02 Jun 2013 21:13:55 GMT

Thanks for that David. I have contacted Mike Martin. I think a kitten is probably too small for catheterisation, but it is very helpful to give the owners some indications re life expectancy and chances of repair.

Mariette

Re: Cats with murmers - when to investigate?

David Mills — Sun, 02 Jun 2013 16:01:29 GMT

[quote user="mariette asselbergs"]I have just seen a 9 week old 700g kitten for 1st vaccination and had an enormous machine-type murmur L+R plus fremitus. PDA or ventricle septum defect. If PDA is it worth referring for diagnosis and potential treatment? [/quote]

Yes. If a PDA, they can be fixed and the cat can essentially live a normal, healthy life. Not sure on the figures for cats, but for untreated dogs 90% will be in CHF by 1y. Very good outcomes from percatheter occlusions. Won't be cheap.

It is possible to operate via thoracotomy on these and ligate the vessel directly. It can be a fiddly operation, although am aware of some cert holders and GPs that do it successfully (no real specialist tools required), and I have seen 3-4 done on charity cases successfully. Thorascopic approaches have also been documented but you need particular experience and skill for these.

There is some discussion about complications between occlusion and ligation, but these appear to be centre dependent. If you're in kidderminster, Mike Martin in Kenilworth will be your best place.

Re: Cats with murmers - when to investigate?

Anthony Dennison — Fri, 31 May 2013 21:24:32 GMT

[quote user="Richard Sanderson"]Did you consider amlodipine in this case?[/quote]

I may be talking utter bull here, but if my memory is correct I think I heard at a CPD that if using amlodipine it may also be a good idea to add spironolactone, as the amlodipine can affect the RAAS and worsen re-modelling of cardiac tissue

Re: Cats with murmers - when to investigate?

mariette asselbergs — Thu, 30 May 2013 16:54:55 GMT

I have just seen a 9 week old 700g kitten for 1st vaccination and had an enormous machine-type murmur L+R plus fremitus. PDA or ventricle septum defect. If PDA is it worth referring for diagnosis and potential treatment? Or are these cases hopeless anyway.

As you can understand no insurance since this was the first visit ro the vet.....

Mariette

Re: Cats with murmers - when to investigate?

nikki — Wed, 29 May 2013 23:29:56 GMT

BSAVA manual on cardiology suggests amlodipine as 1st line anti-hypertensive in cats with ACEI as additional therapy if needed as unlikely to reduce BP by more than 10mmol/l. This is in cats. In dogs it suggests ACEI as 1st line and amlodipine as additional therapy.

Re: Cats with murmers - when to investigate?

tess — Wed, 29 May 2013 18:17:48 GMT

[quote user="Richard Sanderson"]

[Did you consider amlodipine in this case? What was the BP the next time it was monitored? I sometimes don't think benazepril alone address such marked hypertension...

[/quote]

Good suggestion. I've only just diagnosed it and was planning to add in amlodipine if it hadn't come down at its check up. I was following cascade...

Re: Cats with murmers - when to investigate?

Rob Loxley — Tue, 28 May 2013 18:40:04 GMT

[quote user="Martin Atkinson"][quote user="robloxley"]But getting short and long axis R parasternal views and measuring chamber and wall measurements is not beyond any GP vet, and gives lots of information, surely?[/quote] If you have the equipment and the number of cases to practice on maybe not but practice is the word - at what time do you become truly competent?[/quote]

I think you can become competent at the basic views with a little training and practice - to the point of being able to use the tool to help your decision making process e.g. is the LA enlarged, how contractile is the LV.

Having said this, given that echo in an asymptomatic cat is unlikely to result in treatment (though some very tachycardic, non hyperthroid/hypertensive cats do go on atenolol FWIW), I'll offer but don't often push investigations beyond BP/T4(older cats, though rescued cats are often rather optimistically aged...). When it comes to investigating symptomatic cases it's a really handy tool.

As for paying for itself, in a small practice we'd struggle to justify a doppler model, but given it gets daily use across a range of duties I'm sure our basic machine has paid for itself many many times over.

Re: Cats with murmers - when to investigate?

Martin Atkinson — Tue, 28 May 2013 17:42:39 GMT

[quote user="robloxley"]But getting short and long axis R parasternal views and measuring chamber and wall measurements is not beyond any GP vet, and gives lots of information, surely?[/quote] If you have the equipment and the number of cases to practice on maybe not but practice is the word - at what time do you become truly competent? Already stated in this thread even a specialist at a vet school referral clinic got one wrong and had to backtrack o his advice when asked to review the case. There are some things I know I'm very good at, others I accept I'm not, orthopaedics for one, this is something I would like to master but as said I cannot justify the outlay for the equipment.

Re: Cats with murmers - when to investigate?

Rob Loxley — Tue, 28 May 2013 16:29:23 GMT

[quote user="Martin Atkinson"]I think that echocardiography is a task that should only be performed by a speclalist.[/quote]

But getting short and long axis R parasternal views and measuring chamber and wall measurements is not beyond any GP vet, and gives lots of information, surely?

Re: Cats with murmers - when to investigate?

Martin Atkinson — Tue, 28 May 2013 12:39:12 GMT

[quote user="David Mills"]Am I right in thinking you don't echo patients yourself? [/quote] I think that echocardiography is a task that should only be performed by a speclalist. My venerable ultrasound machine died a while ago and has not been replaced, because the number of times I actually need it to make a diagnosis which can't be reached by other means doesn't justify the outlay at my stage of career. Even if I had bitten the bullet I would not be doing echo because I do not consider myself good enough.

Re: Cats with murmers - when to investigate?

Richard Sanderson — Mon, 27 May 2013 22:18:42 GMT

[quote user="tess"]

[quote user="David Mills"]

How old is the cat? If >11 then t4 useful, also BP at any age. Bloods, urine unlikely to be useful at this stage.

[/quote]

Last one I saw with a heart murmur (grade2) had a BP of 275, and the bloods showed a raised urea and creatinine. It's now on Fortekor, aged 8.

[/quote]

Did you consider amlodipine in this case? What was the BP the next time it was monitored? I sometimes don't think benazepril alone address such marked hypertension...

Re: Cats with murmers - when to investigate?

Richard Sanderson — Mon, 27 May 2013 21:50:32 GMT

[quote user="David Mills"]

[quote user="Martin Atkinson"]Here is my controversial thought of the day, I sometimes feel that those who have expensive echocardiography equipment are a bit scared of the test as it may make their equipment redundant.[/quote]

Am I right in thinking you don't echo patients yourself?

[quote user="Richard Sanderson"]Although a very unlikely diagnosis, I often find it is overlooked.[/quote]

As in overlooked on differential lists or overlooked as a definitive diagnosis i.e. you have diagnosed lots (or lots more than the exceedingly rare number of published cat cases) of these? If so, on what criteria have you based the diagnosis? Genuinely interested.

[/quote]

Overlooked on differential lists. Must say only ever seen 1 definitive case when I was a student at The University. Saw 1 I was pretty convinced was, but given finances, never able to definitively diagnose (though did respond to 48hrs IV amox+clav 20mg/kg TID followed by 2 weeks at ~15mg/kg TID and then further 4 weeks at ~15mg/kg BID). And murmur resolved so maybe ....

Re: Cats with murmers - when to investigate?

tess — Mon, 27 May 2013 21:43:45 GMT

[quote user="David Mills"]

How old is the cat? If >11 then t4 useful, also BP at any age. Bloods, urine unlikely to be useful at this stage.

[/quote]

Last one I saw with a heart murmur (grade2) had a BP of 275, and the bloods showed a raised urea and creatinine. It's now on Fortekor, aged 8.

Re: Cats with murmers - when to investigate?

Martin Atkinson — Sat, 25 May 2013 11:24:05 GMT

[quote user="Rob Davis"]Do you really find chest x-rays that useful in assessing feline hearts? I think they often have a fairly normal cardiac silhouette with HCM.[/quote] Yes if you measure VHS rather than just assess the shape. IME the VHS will increase even in HCM although the silhouette may look the same shape.

Re: Cats with murmers - when to investigate?

Liz w — Sat, 25 May 2013 00:29:42 GMT

Thanks everyone, it has really helped having this discussion. I've found some archived cardiology webinars, so iVe started working my way through those as well.

Re: Cats with murmers - when to investigate?

John Flynn — Fri, 24 May 2013 20:33:20 GMT

[quote user="David Mills"]

Yes I'm aware of how to do it, and that it can be done from raw data, I just don't think its useful in our studies with small numbers and without any (real) idea of prevalence in the population as a whole.

[/quote]

I see your point about small numbers in studies, but I still think splitting the data even into 3 groups (yes/maybe/no) is more helpful than a traditional "cut-off" with positive/negative and associated sens/spec %'s. (I appreciate that Idexx have done this with SpecCPL and proBNP)

Trying to stay vaguely on topic, I've not looked at any of the studies w.r.t. feline proBNP, but on the canine side of things I tried to get my head around how to meaningfully interpret a result in a symptomatic patient:

There was a pretty useful sounding paper in JAVMA last year entitled: "Evaluation of plasma N-terminal pro-B-type natriuretic peptide concentrations in dogs with and without cardiac disease" and they obviously generated a lot of data on around 1000 dogs from memory (and I'm not going to dispute whether those dogs were actually in heart failure or not and start critiquing the study further!). They then condensed this down to one or two cut-off values and produced an ROC curve illustrated with only a single test-cut-off and didn't provide enough info in the paper to allow the reader to interpret their findings to any greater degree. I think grouping the data into several categories (e.g. in steps of 500pmol/l) would have allowed more interpretation of an individual result in light of their findings. If I have a proBNP of 3000 in a dog and interpret that identically to a result of 1900, then I'm saying that the level of the result doesn't matter; obviously no-one does this, but what I'm saying is that quantifying it a little more when the magnitude of the test result is correlated with the likelihood of disease absence/presence in the test population being investigated can be helpful rather than just interpreting different "positive" results in light of my own subjectivity. Even with subjectivity, likelihood ratios can be useful as you can estimate your pre-test odds (just ask yourself, based on your clinical judgement and investigations to date, e.g. I'm 60% sure that this dog has dyspnoea due to cardiac disease) and then update that to a post-test odds based on your result. I can't see how presenting this data with more than one or two cut-offs is not more useful? If you're doing a test and interpreting the result based on the available data, then why not use more of that data for your interpretation?

Re: Cats with murmers - when to investigate?

David Mills — Fri, 24 May 2013 20:13:58 GMT

Am I right in thinking you don't echo patients yourself?

[quote user="Richard Sanderson"]Although a very unlikely diagnosis, I often find it is overlooked.[/quote]

Re: Cats with murmers - when to investigate?

Rob Davis — Fri, 24 May 2013 20:00:25 GMT

[quote user="Martin Atkinson"]As a minimum I would X-ray the heart/chest and look for evidence of cardiomegaly/pulmonary changes, establish a baseline VHS which can be compared later (>7.5 is abnormal)[/quote]

Do you really find chest x-rays that useful in assessing feline hearts? I think they often have a fairly normal cardiac silhouette with HCM.

Re: Cats with murmers - when to investigate?

Richard Sanderson — Fri, 24 May 2013 15:16:26 GMT

I think one of the most important things to assess Liz is whether this is a murmur that has been noted previously or whether it is 'new'. If it is new it would be useful to see the time that has elapsed since the last consultation to get a idea of timeframe of development. One would also suppose it would vary if the murmur was accompanied by an arrythmia or a weight loss (a reason to ensure an animal is weighed and the figure added to the records at each visit).

I think with all new murmurs it is worth considering endocarditis, and especially if a more detailed history reveals subtle clinical signs. Although a very unlikely diagnosis, I often find it is overlooked. Consideration should be made to hyperthyroidism and hypertension in a cat especially if over 8 years of age. Beyond that I think an echocardiogram would seem the most appropriate - least invasive, no requirement for sedation and can provide much information relatively cheaply and quickly. I tend to avoid thoracic radiography in assymtomatic cats as unless the radiographs are inflated under GA, the information gained is very dubious. I tend to use cardiac markers such as proBNP and troponin for symptomatic patients.

Re: Cats with murmers - when to investigate?

Martin Atkinson — Fri, 24 May 2013 14:37:19 GMT

Back to the OP. As a minimum I would X-ray the heart/chest and look for evidence of cardiomegaly/pulmonary changes, establish a baseline VHS which can be compared later (>7.5 is abnormal) and test NT-proBNP (regulars to this forum know my enthusiasm for this test). If there is an abnormality of either of these I would recommend a referral to a cardiologist for echo. Second wave of investigation would be a basic blood profile, T4 if there is clinical suspicion hyperthyroidism, and BP. Third tier ECG if there is a hint of arrhythmia. Contrary to what some others may say, in my experience NT-proBNP is an excellent tool at predicting cardiac disease and monitoring its progress and correlates well with other means of investigation. Here is my controversial thought of the day, I sometimes feel that those who have expensive echocardiography equipment are a bit scared of the test as it may make their equipment redundant. (Opens Pandora's box!)

Re: Cats with murmers - when to investigate?

David Mills — Fri, 24 May 2013 14:09:47 GMT

[quote user="John Flynn"]

[quote user="David Mills"]No it wouldn't.[/quote]

It's jsut a matter of splitting the data into more than 2 groups if the test has a quantitative nature. If the test can be "more" positive or "more" negative, then use that information. Reducing this to a cut-off value with dichotomous positive/negative groupings and then reporting sens/spec for these only is not the best use of data.

e.g. http://www.medcalc.org/manual/likelihood_ratios.php

[/quote]

Re: Cats with murmers - when to investigate?

John Flynn — Fri, 24 May 2013 13:23:21 GMT

[quote user="David Mills"]No it wouldn't.[/quote]

e.g. http://www.medcalc.org/manual/likelihood_ratios.php

Re: Cats with murmers - when to investigate?

David Mills — Fri, 24 May 2013 13:15:37 GMT

[quote user="John Flynn"]If they actually published more raw data, then you could figure out some likelihood ratios/intervals and that would at least utilise the test result better. [/quote]

No it wouldn't. Far more important is the population in which the test is used. In populations with clinical signs, proBNP works well (90%-ish) in differentiating between cardiac and non-cardiac causes. It is likely to work less well in the general populous because it may be raised artificially, there may be confounders, genetic influence etc etc. Likelihood ratios, predictive values etc are only of use if we know the prevalence of disease. Which in cats with heart disease we only have limited knowledge of. In terms of an easily-understandable result, positive and negative (sense/spec) are probably the best we can hope for in the absence of prevalence data - why do you think that the vet literature routinely uses sn/sp instead of e.g. PPV/NPV, ORs/LRs etc when compared to human medicine?

Re: Cats with murmers - when to investigate?

Liz w — Fri, 24 May 2013 13:06:11 GMT

Out of interest, if vets in your practices want to practice procedures for their own experience, such as an echo in this case, would you be happy for the vet to do it FOC, or only if paid for in full?

Re: Cats with murmers - when to investigate?

Liz w — Fri, 24 May 2013 13:00:53 GMT

My approach was similar to what John described above. The owner was happy with the wait and see approach. I did discuss scan and proBNP ( unfortunate name), pushing slightly more towards the blood test as I'm not too confident of my scanning skills. I just now feel that actually I should have been more proactive, and am looking to plan my strategy. The cat in question was a healthy looking 9year old, no goitre, good weight.